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  <div class="headertitle"><div class="title">thread_lcl_str_appender.cpp</div></div>
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<a href="thread__lcl__str__appender_8cpp.html">Go to the documentation of this file.</a><div class="fragment"><div class="line"><a id="l00001" name="l00001"></a><span class="lineno">    1</span><span class="comment">/* Flow</span></div>
<div class="line"><a id="l00002" name="l00002"></a><span class="lineno">    2</span><span class="comment"> * Copyright 2023 Akamai Technologies, Inc.</span></div>
<div class="line"><a id="l00003" name="l00003"></a><span class="lineno">    3</span><span class="comment"> *</span></div>
<div class="line"><a id="l00004" name="l00004"></a><span class="lineno">    4</span><span class="comment"> * Licensed under the Apache License, Version 2.0 (the</span></div>
<div class="line"><a id="l00005" name="l00005"></a><span class="lineno">    5</span><span class="comment"> * &quot;License&quot;); you may not use this file except in</span></div>
<div class="line"><a id="l00006" name="l00006"></a><span class="lineno">    6</span><span class="comment"> * compliance with the License.  You may obtain a copy</span></div>
<div class="line"><a id="l00007" name="l00007"></a><span class="lineno">    7</span><span class="comment"> * of the License at</span></div>
<div class="line"><a id="l00008" name="l00008"></a><span class="lineno">    8</span><span class="comment"> *</span></div>
<div class="line"><a id="l00009" name="l00009"></a><span class="lineno">    9</span><span class="comment"> *   https://www.apache.org/licenses/LICENSE-2.0</span></div>
<div class="line"><a id="l00010" name="l00010"></a><span class="lineno">   10</span><span class="comment"> *</span></div>
<div class="line"><a id="l00011" name="l00011"></a><span class="lineno">   11</span><span class="comment"> * Unless required by applicable law or agreed to in</span></div>
<div class="line"><a id="l00012" name="l00012"></a><span class="lineno">   12</span><span class="comment"> * writing, software distributed under the License is</span></div>
<div class="line"><a id="l00013" name="l00013"></a><span class="lineno">   13</span><span class="comment"> * distributed on an &quot;AS IS&quot; BASIS, WITHOUT WARRANTIES OR</span></div>
<div class="line"><a id="l00014" name="l00014"></a><span class="lineno">   14</span><span class="comment"> * CONDITIONS OF ANY KIND, either express or implied.</span></div>
<div class="line"><a id="l00015" name="l00015"></a><span class="lineno">   15</span><span class="comment"> * See the License for the specific language governing</span></div>
<div class="line"><a id="l00016" name="l00016"></a><span class="lineno">   16</span><span class="comment"> * permissions and limitations under the License. */</span></div>
<div class="line"><a id="l00017" name="l00017"></a><span class="lineno">   17</span><span class="comment"></span> </div>
<div class="line"><a id="l00018" name="l00018"></a><span class="lineno">   18</span><span class="comment">/// @file</span></div>
<div class="line"><a id="l00019" name="l00019"></a><span class="lineno">   19</span><span class="comment"></span><span class="preprocessor">#include &quot;<a class="code" href="thread__lcl__str__appender_8hpp.html">flow/log/detail/thread_lcl_str_appender.hpp</a>&quot;</span></div>
<div class="line"><a id="l00020" name="l00020"></a><span class="lineno">   20</span><span class="preprocessor">#include &lt;boost/move/make_unique.hpp&gt;</span></div>
<div class="line"><a id="l00021" name="l00021"></a><span class="lineno">   21</span> </div>
<div class="line"><a id="l00022" name="l00022"></a><span class="lineno">   22</span><span class="keyword">namespace </span><a class="code hl_namespace" href="namespaceflow_1_1log.html">flow::log</a></div>
<div class="line"><a id="l00023" name="l00023"></a><span class="lineno">   23</span>{</div>
<div class="line"><a id="l00024" name="l00024"></a><span class="lineno">   24</span> </div>
<div class="line"><a id="l00025" name="l00025"></a><span class="lineno">   25</span><span class="comment">// Static initializations.</span></div>
<div class="line"><a id="l00026" name="l00026"></a><span class="lineno">   26</span> </div>
<div class="line"><a id="l00027" name="l00027"></a><span class="lineno">   27</span>boost::thread_specific_ptr&lt;Thread_local_string_appender::Source_obj_to_appender_map&gt;</div>
<div class="line"><a id="l00028" name="l00028"></a><span class="lineno">   28</span>  <a class="code hl_variable" href="classflow_1_1log_1_1Thread__local__string__appender.html#a34ac1baa61cd0c865d844a7ab622b7ea">Thread_local_string_appender::s_this_thread_appender_ptrs</a>;</div>
<div class="line"><a id="l00029" name="l00029"></a><span class="lineno">   29</span> </div>
<div class="line"><a id="l00030" name="l00030"></a><span class="lineno">   30</span><span class="comment">// Implementations.</span></div>
<div class="line"><a id="l00031" name="l00031"></a><span class="lineno">   31</span> </div>
<div class="line"><a id="l00032" name="l00032"></a><span class="lineno">   32</span>Thread_local_string_appender*</div>
<div class="line"><a id="l00033" name="l00033"></a><span class="lineno"><a class="line" href="classflow_1_1log_1_1Thread__local__string__appender.html#a4c67bd1c2f1ccc58288df86abda02d88">   33</a></span>  <a class="code hl_function" href="classflow_1_1log_1_1Thread__local__string__appender.html#a4c67bd1c2f1ccc58288df86abda02d88">Thread_local_string_appender::get_this_thread_string_appender</a>(<span class="keyword">const</span> <a class="code hl_class" href="classflow_1_1util_1_1Unique__id__holder.html">util::Unique_id_holder</a>&amp; source_obj_id) <span class="comment">// Static.</span></div>
<div class="line"><a id="l00034" name="l00034"></a><span class="lineno">   34</span>{</div>
<div class="line"><a id="l00035" name="l00035"></a><span class="lineno">   35</span>  <span class="comment">/* It&#39;s just like an on-demand singleton -- but per thread.  Precisely because it is per thread, this code is</span></div>
<div class="line"><a id="l00036" name="l00036"></a><span class="lineno">   36</span><span class="comment">   * thread-safe unlike a regular on-demand singleton.  Then, after the thread lookup, another lookup obtains the</span></div>
<div class="line"><a id="l00037" name="l00037"></a><span class="lineno">   37</span><span class="comment">   * particular source object&#39;s dedicated appender (for the current thread).  (Reminder: source_obj_id is unique ID</span></div>
<div class="line"><a id="l00038" name="l00038"></a><span class="lineno">   38</span><span class="comment">   * of an object that wants to use appenders.  In theory even a mix of different classes can</span></div>
<div class="line"><a id="l00039" name="l00039"></a><span class="lineno">   39</span><span class="comment">   * co-exist in this system, since IDs are unique across all objects of all types.)</span></div>
<div class="line"><a id="l00040" name="l00040"></a><span class="lineno">   40</span><span class="comment">   *</span></div>
<div class="line"><a id="l00041" name="l00041"></a><span class="lineno">   41</span><span class="comment">   * The crux of it is that the .get() call just below returns a different pointer depending on the current thread;</span></div>
<div class="line"><a id="l00042" name="l00042"></a><span class="lineno">   42</span><span class="comment">   * followed by a presumably quick map lookup.  If the performance of .get() is higher than the performance of creating</span></div>
<div class="line"><a id="l00043" name="l00043"></a><span class="lineno">   43</span><span class="comment">   * a new string, inserter around string, and stream around inserter, then this whole thing is worth it.  Otherwise it</span></div>
<div class="line"><a id="l00044" name="l00044"></a><span class="lineno">   44</span><span class="comment">   * is not.</span></div>
<div class="line"><a id="l00045" name="l00045"></a><span class="lineno">   45</span><span class="comment">   *</span></div>
<div class="line"><a id="l00046" name="l00046"></a><span class="lineno">   46</span><span class="comment">   * Update: Now it might still be worth it, because the fact that each ostream thus stored maintains a</span></div>
<div class="line"><a id="l00047" name="l00047"></a><span class="lineno">   47</span><span class="comment">   * persistent yet independent-from-others formatter state (with the save_formatting_state_and_restore_prev() feature</span></div>
<div class="line"><a id="l00048" name="l00048"></a><span class="lineno">   48</span><span class="comment">   * further helping to manage formatting) guarantees convenient, predictable behavior for users of ostream formatters.</span></div>
<div class="line"><a id="l00049" name="l00049"></a><span class="lineno">   49</span><span class="comment">   * That is to say, this allows user to (say) set chrono::symbol_format formatter for this thread&#39;s logging of</span></div>
<div class="line"><a id="l00050" name="l00050"></a><span class="lineno">   50</span><span class="comment">   * durations; yet without concurrently affecting other threads&#39; output of durations; yet also without having re-apply</span></div>
<div class="line"><a id="l00051" name="l00051"></a><span class="lineno">   51</span><span class="comment">   * that formatter repeatedly just to keep duration output looking a certain way.  So, desiring persistent formatting</span></div>
<div class="line"><a id="l00052" name="l00052"></a><span class="lineno">   52</span><span class="comment">   * for a given stream-writing entity OVER TIME means new-string/inserter-around-string/stream-around-insert being</span></div>
<div class="line"><a id="l00053" name="l00053"></a><span class="lineno">   53</span><span class="comment">   * done for each little stream-writing code snippet is insufficient, even if it were computationally as cheap</span></div>
<div class="line"><a id="l00054" name="l00054"></a><span class="lineno">   54</span><span class="comment">   * as the following lookup. */</span></div>
<div class="line"><a id="l00055" name="l00055"></a><span class="lineno">   55</span> </div>
<div class="line"><a id="l00056" name="l00056"></a><span class="lineno">   56</span>  <a class="code hl_typedef" href="classflow_1_1log_1_1Thread__local__string__appender.html#a4656e713b9ac1c6cdad3adde18de70ec">Source_obj_to_appender_map</a>* appender_ptrs = <a class="code hl_variable" href="classflow_1_1log_1_1Thread__local__string__appender.html#a34ac1baa61cd0c865d844a7ab622b7ea">s_this_thread_appender_ptrs</a>.get();</div>
<div class="line"><a id="l00057" name="l00057"></a><span class="lineno">   57</span>  <span class="keywordflow">if</span> (!appender_ptrs)</div>
<div class="line"><a id="l00058" name="l00058"></a><span class="lineno">   58</span>  {</div>
<div class="line"><a id="l00059" name="l00059"></a><span class="lineno">   59</span>    <span class="comment">// Uncommon code path.</span></div>
<div class="line"><a id="l00060" name="l00060"></a><span class="lineno">   60</span> </div>
<div class="line"><a id="l00061" name="l00061"></a><span class="lineno">   61</span>    appender_ptrs = <span class="keyword">new</span> <a class="code hl_typedef" href="classflow_1_1log_1_1Thread__local__string__appender.html#a4656e713b9ac1c6cdad3adde18de70ec">Source_obj_to_appender_map</a>;</div>
<div class="line"><a id="l00062" name="l00062"></a><span class="lineno">   62</span>    <a class="code hl_variable" href="classflow_1_1log_1_1Thread__local__string__appender.html#a34ac1baa61cd0c865d844a7ab622b7ea">s_this_thread_appender_ptrs</a>.reset(appender_ptrs);</div>
<div class="line"><a id="l00063" name="l00063"></a><span class="lineno">   63</span> </div>
<div class="line"><a id="l00064" name="l00064"></a><span class="lineno">   64</span>    assert(appender_ptrs == <a class="code hl_variable" href="classflow_1_1log_1_1Thread__local__string__appender.html#a34ac1baa61cd0c865d844a7ab622b7ea">s_this_thread_appender_ptrs</a>.get());</div>
<div class="line"><a id="l00065" name="l00065"></a><span class="lineno">   65</span> </div>
<div class="line"><a id="l00066" name="l00066"></a><span class="lineno">   66</span>    <span class="comment">/* Note about cleanup: `delete appender_ptrs;` will be executed by thread_specific_ptr when thread exits.</span></div>
<div class="line"><a id="l00067" name="l00067"></a><span class="lineno">   67</span><span class="comment">     * Therefore any per-thread memory is not leaked past the thread&#39;s lifetime.  However, for a given thread,</span></div>
<div class="line"><a id="l00068" name="l00068"></a><span class="lineno">   68</span><span class="comment">     * per-object-ID memory IS leaked even when the corresponding object disappears; we provide no mechanism</span></div>
<div class="line"><a id="l00069" name="l00069"></a><span class="lineno">   69</span><span class="comment">     * to free this.  See class doc header for discussion. */</span></div>
<div class="line"><a id="l00070" name="l00070"></a><span class="lineno">   70</span>  }</div>
<div class="line"><a id="l00071" name="l00071"></a><span class="lineno">   71</span> </div>
<div class="line"><a id="l00072" name="l00072"></a><span class="lineno">   72</span>  <a class="code hl_typedef" href="classflow_1_1log_1_1Thread__local__string__appender.html#a4656e713b9ac1c6cdad3adde18de70ec">Source_obj_to_appender_map</a>&amp; appender_ptrs_map = *appender_ptrs;</div>
<div class="line"><a id="l00073" name="l00073"></a><span class="lineno">   73</span> </div>
<div class="line"><a id="l00074" name="l00074"></a><span class="lineno">   74</span>  <span class="keyword">const</span> <span class="keyword">auto</span>&amp; <span class="keywordtype">id</span> = source_obj_id.<a class="code hl_function" href="classflow_1_1util_1_1Unique__id__holder.html#a24742b697933e623df30056aebbebfae">unique_id</a>();</div>
<div class="line"><a id="l00075" name="l00075"></a><span class="lineno">   75</span>  <span class="keyword">auto</span>&amp; appender_ptr_ref = appender_ptrs_map[id]; <span class="comment">// (Reference to) smart pointer directly in the map.</span></div>
<div class="line"><a id="l00076" name="l00076"></a><span class="lineno">   76</span>  <span class="keywordflow">if</span> (!appender_ptr_ref)</div>
<div class="line"><a id="l00077" name="l00077"></a><span class="lineno">   77</span>  {</div>
<div class="line"><a id="l00078" name="l00078"></a><span class="lineno">   78</span>    <span class="comment">/* Uncommon code path.  appender_ptr (inside the map) was just initialized to null smart pointer.  Un-null it.</span></div>
<div class="line"><a id="l00079" name="l00079"></a><span class="lineno">   79</span><span class="comment">     * Because it&#39;s a smart pointer, not a raw one, deleting the map will delete the object allocated here. */</span></div>
<div class="line"><a id="l00080" name="l00080"></a><span class="lineno">   80</span>    appender_ptr_ref.reset(<span class="keyword">new</span> <a class="code hl_class" href="classflow_1_1log_1_1Thread__local__string__appender.html">Thread_local_string_appender</a>);</div>
<div class="line"><a id="l00081" name="l00081"></a><span class="lineno">   81</span>  }</div>
<div class="line"><a id="l00082" name="l00082"></a><span class="lineno">   82</span> </div>
<div class="line"><a id="l00083" name="l00083"></a><span class="lineno">   83</span>  <span class="comment">/* You may be rightly alarmed that .get() is used and even returned outside the current block.</span></div>
<div class="line"><a id="l00084" name="l00084"></a><span class="lineno">   84</span><span class="comment">   * In this case, it is definitely safe: The underlying pointer is deleted only on .reset() or destruction</span></div>
<div class="line"><a id="l00085" name="l00085"></a><span class="lineno">   85</span><span class="comment">   * of this pointer; .reset() is called only once and was just done above; and destruction occurs only</span></div>
<div class="line"><a id="l00086" name="l00086"></a><span class="lineno">   86</span><span class="comment">   * when the thread exits.  Since the returned object is to be, by definition (it&#39;s in the name!) used only</span></div>
<div class="line"><a id="l00087" name="l00087"></a><span class="lineno">   87</span><span class="comment">   * in the current thread, any attempt to use it in another thread is a blatant mis-use and need not be considered.</span></div>
<div class="line"><a id="l00088" name="l00088"></a><span class="lineno">   88</span><span class="comment">   * (Why not return a smart pointer anyway?  Well, why impose on outside caller the associated syntactic complexities,</span></div>
<div class="line"><a id="l00089" name="l00089"></a><span class="lineno">   89</span><span class="comment">   * when it would be done due to internal implementation details in the first place?  There are other reasons, but</span></div>
<div class="line"><a id="l00090" name="l00090"></a><span class="lineno">   90</span><span class="comment">   * that one is enough, even if they didn&#39;t exist.) */</span></div>
<div class="line"><a id="l00091" name="l00091"></a><span class="lineno">   91</span>  <span class="keywordflow">return</span> appender_ptr_ref.get();</div>
<div class="line"><a id="l00092" name="l00092"></a><span class="lineno">   92</span>}</div>
<div class="line"><a id="l00093" name="l00093"></a><span class="lineno">   93</span> </div>
<div class="line"><a id="l00094" name="l00094"></a><span class="lineno"><a class="line" href="classflow_1_1log_1_1Thread__local__string__appender.html#ad6eb4b32757f9df9823a3ee9073fa9b7">   94</a></span><a class="code hl_function" href="classflow_1_1log_1_1Thread__local__string__appender.html#ad6eb4b32757f9df9823a3ee9073fa9b7">Thread_local_string_appender::Thread_local_string_appender</a>() :</div>
<div class="line"><a id="l00095" name="l00095"></a><span class="lineno">   95</span>  m_target_appender_ostream_prev_os_state</div>
<div class="line"><a id="l00096" name="l00096"></a><span class="lineno">   96</span>    (boost::movelib::make_unique&lt;boost::io::ios_all_saver&gt;(m_target_appender_ostream.os()))</div>
<div class="line"><a id="l00097" name="l00097"></a><span class="lineno">   97</span>{</div>
<div class="line"><a id="l00098" name="l00098"></a><span class="lineno">   98</span>  <span class="comment">// Nothing else.</span></div>
<div class="line"><a id="l00099" name="l00099"></a><span class="lineno">   99</span>}</div>
<div class="line"><a id="l00100" name="l00100"></a><span class="lineno">  100</span> </div>
<div class="line"><a id="l00101" name="l00101"></a><span class="lineno"><a class="line" href="classflow_1_1log_1_1Thread__local__string__appender.html#af8808ca3accc5384a627bb806de4e4b1">  101</a></span>std::ostream* <a class="code hl_function" href="classflow_1_1log_1_1Thread__local__string__appender.html#af8808ca3accc5384a627bb806de4e4b1">Thread_local_string_appender::fresh_appender_ostream</a>()</div>
<div class="line"><a id="l00102" name="l00102"></a><span class="lineno">  102</span>{</div>
<div class="line"><a id="l00103" name="l00103"></a><span class="lineno">  103</span>  <a class="code hl_variable" href="classflow_1_1log_1_1Thread__local__string__appender.html#a7bb2cd7d173ddc0ca3075d0475015f96">m_target_appender_ostream</a>.<a class="code hl_function" href="classflow_1_1util_1_1String__ostream.html#a55008c2e651cfc832182a941284f7e7e">str_clear</a>();</div>
<div class="line"><a id="l00104" name="l00104"></a><span class="lineno">  104</span>  <span class="keywordflow">return</span> <a class="code hl_function" href="classflow_1_1log_1_1Thread__local__string__appender.html#a64383811f529af676dde0028f61831f7">appender_ostream</a>();</div>
<div class="line"><a id="l00105" name="l00105"></a><span class="lineno">  105</span>}</div>
<div class="line"><a id="l00106" name="l00106"></a><span class="lineno">  106</span> </div>
<div class="line"><a id="l00107" name="l00107"></a><span class="lineno"><a class="line" href="classflow_1_1log_1_1Thread__local__string__appender.html#a64383811f529af676dde0028f61831f7">  107</a></span>std::ostream* <a class="code hl_function" href="classflow_1_1log_1_1Thread__local__string__appender.html#a64383811f529af676dde0028f61831f7">Thread_local_string_appender::appender_ostream</a>()</div>
<div class="line"><a id="l00108" name="l00108"></a><span class="lineno">  108</span>{</div>
<div class="line"><a id="l00109" name="l00109"></a><span class="lineno">  109</span>  <span class="comment">// @todo Maybe we should also expose ostream&amp; instead of pointer, if only for consistency.</span></div>
<div class="line"><a id="l00110" name="l00110"></a><span class="lineno">  110</span>  <span class="keywordflow">return</span> &amp;(<a class="code hl_variable" href="classflow_1_1log_1_1Thread__local__string__appender.html#a7bb2cd7d173ddc0ca3075d0475015f96">m_target_appender_ostream</a>.<a class="code hl_function" href="classflow_1_1util_1_1String__ostream.html#a7e64b069ae0e221952068c13fdc0f080">os</a>());</div>
<div class="line"><a id="l00111" name="l00111"></a><span class="lineno">  111</span>}</div>
<div class="line"><a id="l00112" name="l00112"></a><span class="lineno">  112</span> </div>
<div class="line"><a id="l00113" name="l00113"></a><span class="lineno"><a class="line" href="classflow_1_1log_1_1Thread__local__string__appender.html#a2ac7b443898adf1696d0f24f87481520">  113</a></span><span class="keywordtype">void</span> <a class="code hl_function" href="classflow_1_1log_1_1Thread__local__string__appender.html#a2ac7b443898adf1696d0f24f87481520">Thread_local_string_appender::save_formatting_state_and_restore_prev</a>()</div>
<div class="line"><a id="l00114" name="l00114"></a><span class="lineno">  114</span>{</div>
<div class="line"><a id="l00115" name="l00115"></a><span class="lineno">  115</span>  <span class="keyword">using </span>boost::io::ios_all_saver;</div>
<div class="line"><a id="l00116" name="l00116"></a><span class="lineno">  116</span> </div>
<div class="line"><a id="l00117" name="l00117"></a><span class="lineno">  117</span>  <span class="comment">/* Due to smart pointer mechanics and function call expression evaluation order semantics, this does the following:</span></div>
<div class="line"><a id="l00118" name="l00118"></a><span class="lineno">  118</span><span class="comment">   * - Inside reset() parentheses, new ios_all_saver *X is created.</span></div>
<div class="line"><a id="l00119" name="l00119"></a><span class="lineno">  119</span><span class="comment">   *   - X-&gt;ios_all_saver() runs: the current state of the ostream is saved in *X.</span></div>
<div class="line"><a id="l00120" name="l00120"></a><span class="lineno">  120</span><span class="comment">   * - Inside reset() method, the unique_ptr&lt;&gt;&#39;s internal saved pointer is replaced with X.</span></div>
<div class="line"><a id="l00121" name="l00121"></a><span class="lineno">  121</span><span class="comment">   *   - Since the previous saved pointer Y is replaced, *Y is destroyed.</span></div>
<div class="line"><a id="l00122" name="l00122"></a><span class="lineno">  122</span><span class="comment">   *     - Y-&gt;~ios_all_saver() runs: the stated saved at *Y&#39;s construction is restored to the ostream.</span></div>
<div class="line"><a id="l00123" name="l00123"></a><span class="lineno">  123</span><span class="comment">   *</span></div>
<div class="line"><a id="l00124" name="l00124"></a><span class="lineno">  124</span><span class="comment">   * The key insight is that X saved now will be the Y at the present method&#39;s next invocation.  Thus the inductive</span></div>
<div class="line"><a id="l00125" name="l00125"></a><span class="lineno">  125</span><span class="comment">   * chain is built.  The induction base is that *X is the clean just-constructed ostream&#39;s formatting. */</span></div>
<div class="line"><a id="l00126" name="l00126"></a><span class="lineno">  126</span>  <a class="code hl_variable" href="classflow_1_1log_1_1Thread__local__string__appender.html#aebc7ceab35e8201f0c60b59a0cc93ca3">m_target_appender_ostream_prev_os_state</a> = boost::movelib::make_unique&lt;ios_all_saver&gt;(<a class="code hl_variable" href="classflow_1_1log_1_1Thread__local__string__appender.html#a7bb2cd7d173ddc0ca3075d0475015f96">m_target_appender_ostream</a>.<a class="code hl_function" href="classflow_1_1util_1_1String__ostream.html#a7e64b069ae0e221952068c13fdc0f080">os</a>());</div>
<div class="line"><a id="l00127" name="l00127"></a><span class="lineno">  127</span>}</div>
<div class="line"><a id="l00128" name="l00128"></a><span class="lineno">  128</span> </div>
<div class="line"><a id="l00129" name="l00129"></a><span class="lineno"><a class="line" href="classflow_1_1log_1_1Thread__local__string__appender.html#a3f1a93d0c468efeafd83fb10e104905f">  129</a></span><span class="keyword">const</span> std::string&amp; <a class="code hl_function" href="classflow_1_1log_1_1Thread__local__string__appender.html#a3f1a93d0c468efeafd83fb10e104905f">Thread_local_string_appender::target_contents</a>()<span class="keyword"> const</span></div>
<div class="line"><a id="l00130" name="l00130"></a><span class="lineno">  130</span><span class="keyword"></span>{</div>
<div class="line"><a id="l00131" name="l00131"></a><span class="lineno">  131</span>  <span class="keywordflow">return</span> <a class="code hl_variable" href="classflow_1_1log_1_1Thread__local__string__appender.html#a7bb2cd7d173ddc0ca3075d0475015f96">m_target_appender_ostream</a>.<a class="code hl_function" href="classflow_1_1util_1_1String__ostream.html#aa7682e71a5e96955a52643e63bf97ad0">str</a>();</div>
<div class="line"><a id="l00132" name="l00132"></a><span class="lineno">  132</span>}</div>
<div class="line"><a id="l00133" name="l00133"></a><span class="lineno">  133</span> </div>
<div class="line"><a id="l00134" name="l00134"></a><span class="lineno">  134</span>} <span class="comment">// namespace flow::log</span></div>
<div class="ttc" id="aclassflow_1_1log_1_1Thread__local__string__appender_html"><div class="ttname"><a href="classflow_1_1log_1_1Thread__local__string__appender.html">flow::log::Thread_local_string_appender</a></div><div class="ttdoc">Internal flow::log class that facilitates a more efficient way to get util::ostream_op_to_string() be...</div><div class="ttdef"><b>Definition:</b> <a href="thread__lcl__str__appender_8hpp_source.html#l00149">thread_lcl_str_appender.hpp:151</a></div></div>
<div class="ttc" id="aclassflow_1_1log_1_1Thread__local__string__appender_html_a2ac7b443898adf1696d0f24f87481520"><div class="ttname"><a href="classflow_1_1log_1_1Thread__local__string__appender.html#a2ac7b443898adf1696d0f24f87481520">flow::log::Thread_local_string_appender::save_formatting_state_and_restore_prev</a></div><div class="ttdeci">void save_formatting_state_and_restore_prev()</div><div class="ttdoc">Saves the formatting state of the ostream returned by appender_ostream() and sets that same ostream t...</div><div class="ttdef"><b>Definition:</b> <a href="thread__lcl__str__appender_8cpp_source.html#l00113">thread_lcl_str_appender.cpp:113</a></div></div>
<div class="ttc" id="aclassflow_1_1log_1_1Thread__local__string__appender_html_a34ac1baa61cd0c865d844a7ab622b7ea"><div class="ttname"><a href="classflow_1_1log_1_1Thread__local__string__appender.html#a34ac1baa61cd0c865d844a7ab622b7ea">flow::log::Thread_local_string_appender::s_this_thread_appender_ptrs</a></div><div class="ttdeci">static boost::thread_specific_ptr&lt; Source_obj_to_appender_map &gt; s_this_thread_appender_ptrs</div><div class="ttdoc">Thread-local storage for each thread's map storing objects of this class (lazily set to non-null on 1...</div><div class="ttdef"><b>Definition:</b> <a href="thread__lcl__str__appender_8hpp_source.html#l00295">thread_lcl_str_appender.hpp:295</a></div></div>
<div class="ttc" id="aclassflow_1_1log_1_1Thread__local__string__appender_html_a3f1a93d0c468efeafd83fb10e104905f"><div class="ttname"><a href="classflow_1_1log_1_1Thread__local__string__appender.html#a3f1a93d0c468efeafd83fb10e104905f">flow::log::Thread_local_string_appender::target_contents</a></div><div class="ttdeci">const std::string &amp; target_contents() const</div><div class="ttdoc">Read-only accessor for the contents of the string, as written to it since the last fresh_appender_ost...</div><div class="ttdef"><b>Definition:</b> <a href="thread__lcl__str__appender_8cpp_source.html#l00129">thread_lcl_str_appender.cpp:129</a></div></div>
<div class="ttc" id="aclassflow_1_1log_1_1Thread__local__string__appender_html_a4656e713b9ac1c6cdad3adde18de70ec"><div class="ttname"><a href="classflow_1_1log_1_1Thread__local__string__appender.html#a4656e713b9ac1c6cdad3adde18de70ec">flow::log::Thread_local_string_appender::Source_obj_to_appender_map</a></div><div class="ttdeci">boost::unordered_map&lt; util::Unique_id_holder::id_t, boost::movelib::unique_ptr&lt; Thread_local_string_appender &gt; &gt; Source_obj_to_appender_map</div><div class="ttdoc">Short-hand for map of a given thread's appender objects indexed by the IDs of their respective source...</div><div class="ttdef"><b>Definition:</b> <a href="thread__lcl__str__appender_8hpp_source.html#l00276">thread_lcl_str_appender.hpp:277</a></div></div>
<div class="ttc" id="aclassflow_1_1log_1_1Thread__local__string__appender_html_a4c67bd1c2f1ccc58288df86abda02d88"><div class="ttname"><a href="classflow_1_1log_1_1Thread__local__string__appender.html#a4c67bd1c2f1ccc58288df86abda02d88">flow::log::Thread_local_string_appender::get_this_thread_string_appender</a></div><div class="ttdeci">static Thread_local_string_appender * get_this_thread_string_appender(const util::Unique_id_holder &amp;source_obj_id)</div><div class="ttdoc">Returns a pointer to the exactly one Thread_local_string_appender object that is accessible from the ...</div><div class="ttdef"><b>Definition:</b> <a href="thread__lcl__str__appender_8cpp_source.html#l00033">thread_lcl_str_appender.cpp:33</a></div></div>
<div class="ttc" id="aclassflow_1_1log_1_1Thread__local__string__appender_html_a64383811f529af676dde0028f61831f7"><div class="ttname"><a href="classflow_1_1log_1_1Thread__local__string__appender.html#a64383811f529af676dde0028f61831f7">flow::log::Thread_local_string_appender::appender_ostream</a></div><div class="ttdeci">std::ostream * appender_ostream()</div><div class="ttdoc">Same as fresh_appender_ostream() but does not clear the result string, enabling piecemeal writing to ...</div><div class="ttdef"><b>Definition:</b> <a href="thread__lcl__str__appender_8cpp_source.html#l00107">thread_lcl_str_appender.cpp:107</a></div></div>
<div class="ttc" id="aclassflow_1_1log_1_1Thread__local__string__appender_html_a7bb2cd7d173ddc0ca3075d0475015f96"><div class="ttname"><a href="classflow_1_1log_1_1Thread__local__string__appender.html#a7bb2cd7d173ddc0ca3075d0475015f96">flow::log::Thread_local_string_appender::m_target_appender_ostream</a></div><div class="ttdeci">util::String_ostream m_target_appender_ostream</div><div class="ttdoc">The target string wrapped by an ostream. Emptied at construction and in fresh_appender_ostream() only...</div><div class="ttdef"><b>Definition:</b> <a href="thread__lcl__str__appender_8hpp_source.html#l00298">thread_lcl_str_appender.hpp:298</a></div></div>
<div class="ttc" id="aclassflow_1_1log_1_1Thread__local__string__appender_html_ad6eb4b32757f9df9823a3ee9073fa9b7"><div class="ttname"><a href="classflow_1_1log_1_1Thread__local__string__appender.html#ad6eb4b32757f9df9823a3ee9073fa9b7">flow::log::Thread_local_string_appender::Thread_local_string_appender</a></div><div class="ttdeci">Thread_local_string_appender()</div><div class="ttdoc">Initializes object with an empty string and the streams machinery available to write to that string.</div><div class="ttdef"><b>Definition:</b> <a href="thread__lcl__str__appender_8cpp_source.html#l00094">thread_lcl_str_appender.cpp:94</a></div></div>
<div class="ttc" id="aclassflow_1_1log_1_1Thread__local__string__appender_html_aebc7ceab35e8201f0c60b59a0cc93ca3"><div class="ttname"><a href="classflow_1_1log_1_1Thread__local__string__appender.html#aebc7ceab35e8201f0c60b59a0cc93ca3">flow::log::Thread_local_string_appender::m_target_appender_ostream_prev_os_state</a></div><div class="ttdeci">boost::movelib::unique_ptr&lt; boost::io::ios_all_saver &gt; m_target_appender_ostream_prev_os_state</div><div class="ttdoc">Stores the ostream formatter state from construction time or time of last save_formatting_state_and_r...</div><div class="ttdef"><b>Definition:</b> <a href="thread__lcl__str__appender_8hpp_source.html#l00311">thread_lcl_str_appender.hpp:311</a></div></div>
<div class="ttc" id="aclassflow_1_1log_1_1Thread__local__string__appender_html_af8808ca3accc5384a627bb806de4e4b1"><div class="ttname"><a href="classflow_1_1log_1_1Thread__local__string__appender.html#af8808ca3accc5384a627bb806de4e4b1">flow::log::Thread_local_string_appender::fresh_appender_ostream</a></div><div class="ttdeci">std::ostream * fresh_appender_ostream()</div><div class="ttdoc">Clears the internally stored string (accessible for reading via target_contents()),...</div><div class="ttdef"><b>Definition:</b> <a href="thread__lcl__str__appender_8cpp_source.html#l00101">thread_lcl_str_appender.cpp:101</a></div></div>
<div class="ttc" id="aclassflow_1_1util_1_1String__ostream_html_a55008c2e651cfc832182a941284f7e7e"><div class="ttname"><a href="classflow_1_1util_1_1String__ostream.html#a55008c2e651cfc832182a941284f7e7e">flow::util::String_ostream::str_clear</a></div><div class="ttdeci">void str_clear()</div><div class="ttdoc">Performs std::string::clear() on the object returned by str().</div><div class="ttdef"><b>Definition:</b> <a href="string__ostream_8cpp_source.html#l00048">string_ostream.cpp:48</a></div></div>
<div class="ttc" id="aclassflow_1_1util_1_1String__ostream_html_a7e64b069ae0e221952068c13fdc0f080"><div class="ttname"><a href="classflow_1_1util_1_1String__ostream.html#a7e64b069ae0e221952068c13fdc0f080">flow::util::String_ostream::os</a></div><div class="ttdeci">std::ostream &amp; os()</div><div class="ttdoc">Access to stream that will write to owned string.</div><div class="ttdef"><b>Definition:</b> <a href="string__ostream_8cpp_source.html#l00033">string_ostream.cpp:33</a></div></div>
<div class="ttc" id="aclassflow_1_1util_1_1String__ostream_html_aa7682e71a5e96955a52643e63bf97ad0"><div class="ttname"><a href="classflow_1_1util_1_1String__ostream.html#aa7682e71a5e96955a52643e63bf97ad0">flow::util::String_ostream::str</a></div><div class="ttdeci">const std::string &amp; str() const</div><div class="ttdoc">Read-only access to the string being wrapped.</div><div class="ttdef"><b>Definition:</b> <a href="string__ostream_8cpp_source.html#l00043">string_ostream.cpp:43</a></div></div>
<div class="ttc" id="aclassflow_1_1util_1_1Unique__id__holder_html"><div class="ttname"><a href="classflow_1_1util_1_1Unique__id__holder.html">flow::util::Unique_id_holder</a></div><div class="ttdoc">Each object of this class stores (at construction) and returns (on demand) a numeric ID unique from a...</div><div class="ttdef"><b>Definition:</b> <a href="uniq__id__holder_8hpp_source.html#l00106">uniq_id_holder.hpp:107</a></div></div>
<div class="ttc" id="aclassflow_1_1util_1_1Unique__id__holder_html_a24742b697933e623df30056aebbebfae"><div class="ttname"><a href="classflow_1_1util_1_1Unique__id__holder.html#a24742b697933e623df30056aebbebfae">flow::util::Unique_id_holder::unique_id</a></div><div class="ttdeci">id_t unique_id() const</div><div class="ttdoc">Raw unique ID identifying this object as well as any object of a derived type.</div><div class="ttdef"><b>Definition:</b> <a href="uniq__id__holder_8cpp_source.html#l00053">uniq_id_holder.cpp:53</a></div></div>
<div class="ttc" id="anamespaceflow_1_1log_html"><div class="ttname"><a href="namespaceflow_1_1log.html">flow::log</a></div><div class="ttdoc">Flow module providing logging functionality.</div><div class="ttdef"><b>Definition:</b> <a href="async__file__logger_8cpp_source.html#l00027">async_file_logger.cpp:28</a></div></div>
<div class="ttc" id="athread__lcl__str__appender_8hpp_html"><div class="ttname"><a href="thread__lcl__str__appender_8hpp.html">thread_lcl_str_appender.hpp</a></div></div>
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